Vehicular heating system

ABSTRACT

A vehicular heating system comprising a passenger compartment air-conditioner and a radiative heater which heats a foot area of a passenger, said vehicular heating system detecting foot vent heat which said foot vent air flow has and controlling said passenger compartment air-conditioner and said radiative heater in accordance with that heat.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vehicular heating system which controls a radiative heater and a car air-conditioner linked with each other.

2. Description of the Related Art

In the past, it has been known to place a planar heating element near a foot area of a seat of a vehicle. Japanese Unexamined Patent Publication No. 2010-64681 discloses a vehicular heating system which arranges a planar heating element in an instrument panel of a vehicle so as to heat the inside of the passenger compartment. This planar heating element is arranged in the instrument panel corresponding to the knee to foot part of a seat passenger. At a location corresponding to the foot part side away from the knee part side, the heating density of the planar heating element is raised. Due to this, the surface temperature of the foot part side is raised compared with the knee part side to apply a larger radiative heat from the foot part side than the knee part side. However, in this related art, if considering the air temperature inside of the passenger compartment or simultaneously using the planar heating element and the car air-conditioner without linkage with the car air-conditioner, there was the problem that the warmness sense level at the feet would be insufficient or too high.

SUMMARY OF THE INVENTION

To solve the above problems, the aspect of the invention of claim 1 provides a vehicular heating system comprising a passenger compartment air-conditioner with an air-conditioning unit controlling passenger compartment air-conditioning by calculating a target blowing-out temperature of said air-conditioning unit in accordance with information on the environment inside and outside of the passenger compartment and vehicle operating information, wherein a foot vent air flow of said air-conditioning unit being adjustable, and a radiative heater which heats a foot area of a passenger, said vehicular heating system detecting foot vent heat which said foot vent air flow has and controlling said passenger compartment air-conditioner and said radiative heater in accordance with that heat.

The aspect of the invention of claim 2 provides the aspect of the invention as set forth in claim 1 wherein the system controls the passenger compartment air-conditioner and the radiative heater so that a ratio between the foot vent heat which the foot vent air flow has and the electric power input to the radiative heater gives the same warmness sense level at the feet of the passenger.

Due to this, it is possible to perform control while linked with the car air-conditioner, obtain a satisfactory warmness sense level at the feet, and reduce fuel consumption.

The aspect of the invention of claim 3 provides the aspect of the invention as set forth in claim 2, wherein when the engine water temperature is a predetermined value or more, the system makes the foot vent air flow increase and makes the input electric power of the radiative heater decrease so that the ratio between the foot vent heat which the foot vent air flow has and the electric power input to the radiative heater gives the same warmness sense level at the feet of the passenger and when the engine water temperature is less than the predetermined value, the system makes the foot vent air flow decrease and makes the electric power input to the radiative heater increase so that the ratio between the foot vent heat which the foot vent air flow has and the electric power input to the radiative heater gives the same warmness sense level at the feet of the passenger.

Due to this, by controlling the ratio between the foot vent heat Qf which the foot vent air flow has and the input electric power Q of the radiative heater so as to give the same warmness sense level at the feet of the passenger and using a radiative heater with a large impact on the warmness sense level even with a small input electric power, the fuel efficiency is increased.

The aspect of the invention of claim 4 provides the aspect of the invention as set forth in claim 2, wherein when the engine water temperature is a predetermined value or more, the system turns the radiative heater OFF, and when the engine water temperature is less than the predetermined value, the system turns the radiative heater ON and makes the foot vent air flow decrease and makes the electric power input to the radiative heater increase so that the ratio between the foot vent heat which the foot vent air flow has and the electric power input to the radiative heater gives the same warmness sense level at the feet of the passenger.

Due to this, by controlling the ratio between the foot vent heat Qf which the foot vent air flow has and the input electric power Q of the radiative heater so as to give the same warmness sense level at the feet of the passenger and using a radiative heater with a large impact on the warmness sense level even with a small input electric power, the fuel efficiency is increased and it is not necessary to run the engine just for passenger compartment air-conditioning control.

The aspect of the invention of claim 5 provides the aspect of the invention as set forth in claim 2, wherein the foot vent air flow is a vent air flow of a foot vent.

The aspect of the invention of claim 6 provides the aspect of the invention as set forth in claim 2, wherein the foot vent air flow is a total of a vent air flow of a foot vent and a vent air flow of a knee vent.

The aspect of the invention of claim 7 provides the aspect of the invention as set forth in claim 2, wherein the system adjusts the foot vent air flow by a blower of the air-conditioning unit.

The aspect of the invention of claim 8 provides the aspect of the invention as set forth in claim 2, wherein the system adjusts the foot vent air flow by a door opening degree of a foot vent of the air-conditioning unit.

The aspect of the invention of claim 9 provides the aspect of the invention as set forth in claim 2, wherein the system adjusts the foot vent air flow by a door opening degree of a knee vent of the air-conditioning unit.

The aspect of the invention of claim 10 provides the aspect of the invention as set forth in claim 3, wherein when the engine water temperature is less than a predetermined value, the system makes the foot vent air flow zero.

The aspect of the invention of claim 11 provides the aspect of the invention as set forth in claim 2, wherein the system uses the target blowing-out temperature of the air-conditioning unit, the temperature setting of the air-conditioning unit, an outside air temperature, an inside air temperature, a foot area temperature, or a seat heater temperature as the basis to control the radiative heater ON and OFF.

The aspect of the invention of claim 12 provides a vehicular heating system which adjusts a heating element surface member temperature of a radiative heater which warms a passenger in accordance with temperature information inside the passenger compartment, in which vehicular heating system, before a predetermined time elapses from when heating by the vehicular heating system is turned ON or at the time of elapse, the heating element surface member temperature is controlled based on a setting for which a first upper threshold value where the passenger will not suffer high temperature burn injuries is set and which is set to increase proportionally or in a monotone functional way in accordance with temperature information inside the passenger compartment at below that upper threshold value, and, after a predetermined time elapses from when heating by the vehicular heating system is turned ON, the heating element surface member temperature is controlled to not more than a second upper threshold value where the passenger will not suffer low temperature burn injuries.

Due to this, to enable safe use without concern about high temperature burn injuries or low temperature burn injuries, no matter how the temperature information inside the passenger compartment is set, the temperature of the heating element 2 of the radiative heater 1 is automatically controlled to always be no more than the threshold temperatures for high temperature burn injuries and low temperature burn injuries. Further, the radiative heater can sufficiently contribute to raising the temperature of the foot area in the transitional period and can maintain a predetermined warmness sense level without concern over low temperature burn injuries in the steady state period. The radiative heating enables the legs to be quickly warmed, so this is effective for the transitional period.

The aspect of the invention of claim 13 provides the aspect of the invention as set forth in claim 12, wherein the temperature information inside the passenger compartment is the target blowing-out temperature of the air-conditioning unit which controls the passenger compartment air-conditioning in accordance with information on the environment inside and outside of the passenger compartment. Due to this, it is possible to control the surface member temperature of the heating element of the heating system while linked with the value of the target blowing-out temperature in the case of automatic air-conditioning control so as to enable safe use without concern over high temperature burn injuries and low temperature burn injuries. In the winter season right after a passenger gets in the vehicle and feels cold due to the passenger compartment not being warmed up, the value of the target blowing-out temperature rises to a high temperature, but even in this case, the radiative heater is controlled to a high temperature not causing high temperature burn injuries and therefore the passenger compartment and foot area are quickly warmed. After this, as the value of the target blowing-out temperature TAO falls, the surface member temperature of the heating element of the radiative heater also automatically falls by the same timing, so the feet can be efficiently heated. Therefore, it is possible to maintain a constant warmness sense level at the foot area. Further, there is no waste in the heating by the radiative heater, so energy is saved.

The aspect of the invention of claim 14 provides the aspect of the invention as set forth in claim 12 wherein the temperature information inside the passenger compartment is the temperature setting of the air-conditioning unit which controls the passenger compartment air-conditioning in accordance with information on the environment inside and outside of the passenger compartment.

The aspect of the invention of claim 15 provides the aspect of the invention as set forth in claim 12, wherein the temperature information inside the passenger compartment is the temperature setting when an operating mode of the passenger compartment air-conditioning is manual.

The aspect of the invention of claim 16 provides the aspect of the invention as set forth in claim 12, wherein the temperature information inside the passenger compartment is a foot area temperature.

The aspect of the invention of claim 17 provides the aspect of the invention as set forth in claim 12, wherein the temperature information inside the passenger compartment is a manual temperature setting of the radiative heater.

The aspect of the invention of claim 18 provides the aspect of the invention as set forth in claim 12, wherein the temperature information inside the passenger compartment is a manual temperature setting of a seat heater.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention will become clearer from the following description of the preferred embodiments given with reference to the attached drawings, wherein:

FIG. 1 is a schematic view of a vehicular heating system in one embodiment of the present invention;

FIGS. 2A and 2B are one example of a radiative heater in one embodiment of the present invention. FIG. 2A is a plan view and FIG. 2B is a front view;

FIG. 3 is one example of a graph which shows the relationship between a target blowing-out temperature TAO and foot vent air flow in automatic air-conditioning control;

FIGS. 4A to 4C are views which show relationships between a foot vent heat Qf and heater electric power (power consumption) Q so that the same warmness sense level is obtained, wherein FIGS. 4A to 4C respectively show the relationships of the heater electric power, foot vent heat, and fuel efficiency (liter/100 km) with the foot vent air flow;

FIG. 5 shows an example of an equation which shows the interrelationship of a foot vent air flow Va, input electric power Q of the radiative heater, skin temperature Tsk, etc. in the case of a targeted warmness sense level P;

FIG. 6 is a conceptual flowchart of a modification of a second embodiment of the present invention;

FIG. 7A is an example of a graph which shows the relationship of a target blowing-out temperature TAO and a surface member temperature T of the heating element 2 in a transitional period where the elapsed time t is t1 or less, while FIG. 7B is an example of a graph which shows the relationship of a target blowing-out temperature TAO and a surface member temperature T of the heating element 2 in a steady state period where the elapsed time t is over t1;

FIG. 8 is a graph which shows the relationship between, from the top, a foot area temperature, heating element surface member temperature, and warmness sense level with time;

FIG. 9 is an explanatory view of one example of a method of converting a burn injury threshold temperature at a skin temperature to the surface member temperature T of the heating element 2;

FIG. 10 is one example of the relationship between low temperature burn injuries and time; and

FIG. 11 is a conceptual flow chart of an embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Below, embodiments of the present invention will be explained while referring to the drawings. In the embodiments, the same components are assigned the same reference notations and explanations are omitted.

FIG. 1 is a schematic view of a vehicular heating system in one embodiment of the present invention. A radiative heater 1 is arranged near the top of the feet of the driver at the wall surface below the steering wheel column in the vehicle. FIGS. 2A and 2B show one example of a radiative heater in one embodiment of the present invention. A heating element 2, as shown in FIG. 2, is comprised of an electric heater wire arranged in a snaking fashion. This is formed sandwiched between a surface member and a burn preventing member 3 (material with low heat transfer coefficient). For the heating element 2, instead of an electric heating wire, it is possible to use a heater formed by a resistance member with a PTC (positive temperature coefficient) property formed into a sheet shape.

The vehicular air-conditioning system is comprised of a refrigeration cycle which is comprised of a compressor which is driven by the vehicle drive engine, a condenser, a receiver, an expansion valve, and an evaporator and of an air-conditioning unit (HVAC). The air-conditioning unit has attached to it a blower unit which has blowers and has a plastic air-conditioner case which forms air passages by which air is blown toward the inside of the passenger compartment. Inside this air-conditioner case, an evaporator is housed as a cooling-use heat exchanger and a heater core is housed as a heating use heat exchanger. By controlling the opening degree of an air mix door which is housed inside of the air-conditioning unit (HVAC), the temperature of the air is adjusted to blow air-conditioned air out from defroster vents, face vents, foot vents, and knee vents. Knee vents are sometimes provided and sometimes not, but when there are knee vents, a door is provided for adjusting the ratio of flow rates of the foot vents and the knee vents.

The air-conditioning unit is controlled by an air-conditioning controller ECU. This air-conditioning controller ECU receives as inputs from an inside air temperature sensor, outside air temperature sensor, sunlight sensor which detects the amount of sunlight, and other sensors which detect the heat load of the vehicle, signals such as a detection signal Trm (passenger compartment temperature), Tam (outside air temperature), Ts (sunlight strength signal), etc. and receives as input a temperature setting Tset etc. as control signals from an air-conditioning control panel provided inside the instrument panel. Vehicle operating information, the temperature of an evaporator in the refrigeration cycle, etc. are also input. The air-conditioning controller ECU controls the operating mode, vent mode, blow-out temperature, blowing amount, etc. of the air-conditioned air which is blown out from the air-conditioning unit to the inside of the passenger compartment. To heat the foot area, usually foot vents 11 are provided, but as shown in FIG. 1, both foot vents 11 and knee vents 12 may also be provided.

In automatic air-conditioning control, the air-conditioning controller ECU detects the current passenger compartment temperature, outside air temperature, sunlight strength, and other conditions of the environment inside and outside of the passenger compartment and calculates what temperature the air from the air-conditioning unit is now compared with the temperature which a passenger desires (above temperature setting Tset). This calculated value is called the “target blowing-out temperature TAO” and is a value forming the basis of automatic air-conditioning control (as the general formula of the target blowing-out temperature TAO, target blowing-out temperature=Kset·Tset−Kr·Trm—Kam·Tam−Ks·Ts+C, where Kset, Kr, Kam, and Ks are gains of the signals and C is a constant). Note that, the general air-conditioning control by air-conditioning units and the control of automatic air-conditioners are described in detail in “Automotive Air Conditioning” (Tokyo Denki University Press, Kenichi Fujiwara et al., Sep. 9, 2009), pages 88 to 94. The air-conditioning control by an air-conditioning unit in one embodiment of the present invention is not limited to the basic control such as in “Automotive Air Conditioning” and can be applied to modifications of this as well.

The air-conditioning control panel is provided with an A/C switch for turning air-conditioner operation ON/OFF, an auto air-conditioning switch which switches the operating mode between automatic/manual, ON/OFF switches and manual setters (digital settings or dial settings) for the foot use radiative heater and seat heater, etc. The temperature setting Tset functions in the case where the operating mode is automatic or manual. The information on the environment inside and outside of the passenger compartment indicates the outside air temperature, inside air temperature, target blowing-out temperature TAO, temperature setting Tset, manual temperature setting of the radiative heater or seat heater, foot area temperature, humidity, etc. The vehicle operating information is selected in accordance with need from a broad range of information relating to the vehicle such as the engine water temperature, evaporator temperature in the refrigeration cycle, vehicle speed, air-conditioning operating mode, and vent mode.

First Embodiment

Next, the unique features of radiative heating will be explained, then an embodiment of the present invention will be explained. As shown in FIGS. 2A and 2B, the radiative heater 1 in one embodiment of the present invention is placed near the top of the feet of the driver in the wall surface under the steering wheel column of the vehicle. This efficiently heats the foot parts, which are particularly susceptible to cold and heat in the body, locally by mainly radiant energy.

This embodiment of the present invention makes good use of such features of the radiative heater and aims at satisfying the warmness sense level of the feet while realizing fuel savings by control linked with the car air-conditioner.

An electric heater or other radiative heater uses radiative heat for heating. Therefore, unlike when blowing warm air to warm the legs, a small amount of heat gives the same warmness sense level, so the thermal efficiency is good. A warmness sense level obtained by consuming a high electric power in the foot mode of the vehicular air-conditioning system is obtained at the same warmness sense level by lower electric power by the radiative heater. Therefore, if using a radiative heater, the fuel consumption is improved.

FIG. 3 is an example of a graph which shows the relationship between a target blowing-out temperature TAO and a foot vent air flow in automatic air-conditioning control. Note that, in the present invention, the “vent air flow” indicates the air flow per unit time (m³/h). In the case of there being a knee vent, the foot vent air flow is the total of the foot vent air flow and knee vent air flow.

In automatic air-conditioning control, as seen in FIG. 3, the general practice is to automatically determine the vent air flow in accordance with the target blowing-out temperature TAO. In the present invention, the usual vent air flow in automatic air-conditioning control is deliberately changed and a radiative heater is used to make up for the decreased warmness sense level and as a result give the same warmness sense level. By using a radiative heater, it is possible to make the fuel efficiency increase. Note that, to adjust the vent air flow compared with the normal flow as seen in FIG. 3, it is possible to adjust the blower of the air-conditioning unit (HVAC), the door opening degree of the foot vent, the door opening degree of the knee vent, or the door opening degrees of the two.

The vehicular heating system of the present embodiment is a system which calculates the target blowing-out temperature TAO of the air-conditioning unit HVAC in accordance with information on the environment inside and outside of the passenger compartment and vehicle operating information and controls the passenger compartment air-conditioning. It is provided with a passenger compartment air-conditioner which can adjust the foot vent air flow of the air-conditioning unit (HVAC) and a radiative heater which heats the foot area of a passenger. Further, it controls the passenger compartment air-conditioner and the radiative heater so that the ratio of the foot vent heat Qf which the foot vent air flow has and the input electric power Q of the radiative heater gives the same warmness sense level at the feet of the passenger. Here, the “same warmness sense level” may be not only the warmness sense level of a specific temperature, but also the same warmness sense level having a certain degree of range of warmness sense level. Further, the same warmness sense level targeted is suitably set to “slightly warm”, “neutral”, etc.

FIGS. 4A to 4C are views which show the relationships of the foot vent heat Qf and the heater electric power (power consumption) Q designed to give the same warmness sense level. FIGS. 4A to 4C respectively are views which show the relationships of the heater electric power, foot vent heat, and fuel consumption (liters/100 km) with the foot vent air flow. In the case of most vehicles, the fuel consumption becomes the smallest when the foot vent air flow is zero, but depending on the characteristics of the vehicle, a peak value (minimum power consumption) appears at a certain foot vent air flow as shown in the following formula:

Foot vent heat (Qf)+input electric power of radiative heater (Q)=minimum power consumption

Therefore, the ratio of air flows is adjusted so that the total fuel consumption due to the radiative heater and the air-conditioner becomes the minimum while satisfying the warmness sense level.

Further, in the case of FIGS. 4A to 4C, “the same warmness sense level to be held” is the warmness sense level due to the foot vent air flow in the case where the vent air flows of the different parts are automatically determined in accordance with the target blowing-out temperature TAO in the air-conditioning unit (HVAC) at the time when the radiative heater (heater) is OFF (FIG. 3). The same warmness sense level to be held is not limited to this. It may also be suitably and freely set (the same warmness sense level to be held in this case is determined by the warmness sense level which is determined by the heater at the time of zero foot air flow). It is also possible to constantly maintain a comfortable warmness sense level (for example, warmness sense level 1=slightly warm).

In this way, the embodiment of the present invention features control of the ratio of the foot vent heat Qf which the foot vent air flow has and the input electric power Q of the radiative heater so as to give the same warmness sense level at the feet of the passenger. That is, the present embodiment deliberately reduces the vent air flow by using a radiative heater and performs control so that the same warmness sense level can be held. Due to this, by using a radiative heater which has the large effect of giving a warmness sense level even with little input electric power, it is possible to make the fuel efficiency increase.

Second Embodiment

The next second embodiment considers not only the fuel efficiency due to the characteristics of the radiative heater, but also the characteristics of the vehicle so as to control the passenger compartment air-conditioner and the radiative heater. The air-conditioning unit (HVAC) houses a heater core which acts as a heat exchanger for heating use. This heater core uses the cooling water (warm water) of the vehicle driving motor as a heat source for heating the air. When the engine water temperature of the cooling water of the engine is around a certain predetermined threshold value and the heat source which is used for heating is switched as explained next, the thermal efficiency rises and in turn the fuel economy can be realized.

When utilizing the heater core of the air-conditioning unit (HVAC) for heating, if there is an extra margin of heat as a heat source in the cooling water (warm water) (when the engine water temperature is a certain predetermined value or more), no problem arises in thermal efficiency by utilizing the cooling water (warm water) as a heat source. However, when the cooling water (warm water) no longer has a sufficient margin of heat as a heat source (when the engine water temperature is less than a predetermined value), sometimes a command is issued to deliberately raise the engine speed for passenger compartment air-conditioning control. In particular, in hybrid vehicles (HV's), cars with idling stop systems, and other vehicles in which there are many opportunities for stopping the engine, when there is no longer a sufficient margin of heat as a heat source in the cooling water (warm water), a command is issued to deliberately run the engine for the passenger compartment air-conditioning control. This is not preferable from the viewpoint of the fuel consumption costs. The second embodiment makes improvements to this situation so as to realize lower fuel consumption costs.

That is, when a heat source which can be utilized for heating is sufficiently present in the engine cooling water which flows to the heater core (when the engine water temperature is a certain predetermined value or more), to obtain the same targeted warmness sense level, in heating the foot area of the passengers, the heating is performed by the flow of air which is blown toward the feet in the air-conditioning unit (HVAC). Conversely, if there is no longer an extra margin of heat as a heat source in the cooling water (when the engine water temperature is less than a certain predetermined value), the ratio of the input electric power Q of the radiative heater is made to increase.

If considering this state in terms of the thermal efficiency of the vehicle as a whole, when the engine water temperature is a certain predetermined value or more, for the heat source for heating use, since the engine cooling water has excess heat, the heater core should be relied on more and the input electric power of the radiative heater should be decreased. Further, if the engine water temperature is less than a certain predetermined value, conversely, the input electric power of the radiative heater is made to increase. Due to this, it is possible to avoid ending up running the engine unnecessarily for the passenger compartment air-conditioning control.

When the engine water temperature is a predetermined value or more, the present embodiment makes the foot vent air flow increase and makes the input electric power of the radiative heater decrease so that the ratio of the foot vent heat Qf which the foot vent air flow has and the input electric power Q of the radiative heater gives the same warmness sense level at the feet of the passenger. When the engine water temperature is less than the predetermined value, it makes the foot vent air flow decrease and makes the input electric power of the radiative heater increase so that the ratio of the foot vent heat Qf which the foot vent air flow has and the input electric power Q of the radiative heater gives the same warmness sense level at the feet of the passenger. As the predetermined value of the threshold value of the engine water temperature, while governed by the specifications and characteristics of the vehicle, about 50 to 60° C. or so may be set by experience as a good rule of thumb.

As explained later, with a radiative heater, low temperature burn injuries and high temperature burn injuries (instant burn injuries) sometimes occur. That is, for the skin temperature Tsk at the feet, there is a safe temperature comprised of a threshold temperature. It is also possible to set the input electric power Q of the radiative heater in FIG. 4A from this safe temperature. In this case, the foot vent air flow is determined so as to give the same warmness sense level at the feet of the passenger. It is therefore possible to determine the foot vent heat Qf.

It is also possible to suitably make the foot vent air flow increase or decrease and set the foot vent heat Qf and the input electric power Q of the radiative heater to give the same warmness sense level at the feet of the passenger based on the foot vent air flow determined from the relationship between the target blowing-out temperature TAO and the foot vent air flow in the automatic air-conditioning control of FIG. 3. As shown in FIG. 4C, when the engine water temperature is less than the predetermined value, it is also possible to make the foot vent air flow zero. In this case, the fuel consumption becomes the smallest.

FIG. 5 is one example of a formula which shows the interrelationship of the foot vent air flow Va, the input electric power of the radiative heater (heater electric power) Q, skin temperature Tsk, etc. in the case of a target warmness sense level P. This calculates the required radiative energy for reaching the feet from the amount of heat radiated to the feet when the heater (radiative heater) is turned ON so as to obtain the relationship with the required heater electric power when satisfying the foot warmness sense level P. Using such a formula, it is possible to map the amount of change of the foot vent air flow and the input electric power Q of the radiative heater (heater electric power). In this case, it is possible to determine the foot air flow giving the smallest fuel consumption when the radiative heater is ON from FIG. 4C and determine the heater electric power Q and foot vent heat Qf from FIG. 4A and FIG. 4B. FIGS. 4A to 4C may be prepared in advance so that the skin temperature becomes the safe temperature or less at the same warmness sense level at the feet of the passenger.

As a modification of the second embodiment, it is also possible to turn the radiative heater OFF when the engine water temperature is a predetermined value or more and turn the radiative heater ON when the engine water temperature is less than the predetermined value and make the foot vent air flow decrease and make the input electric power of the radiative heater increase so that the ratio between the foot vent heat Qf which the foot vent air flow has and the input electric power of the radiative heater gives the same warmness sense level at the feet of the passenger.

FIG. 6 is a conceptual flowchart of the modification of the second embodiment of the present invention.

At step 100, it is judged if the engine water temperature is a predetermined value or more. If NO, the routine proceeds to step 101 where the radiative heater is turned ON, then the routine proceeds to step 102. If YES, the routine proceeds to step S104 where the radiative heater is turned OFF. At step 102, a map is utilized to find the amount of change of the foot vent air flow, then at step 103, a door opening degree and input electric power Q of the radiative heater are determined.

In the flowchart of other embodiments of the present invention, at step 100, instead of the engine water temperature, any of the target blowing-out temperature (TAO) of the air-conditioning unit (HVAC), the temperature setting of the air-conditioning unit (HVAC), the outside air temperature, the inside air temperature, the foot area temperature, or the seat heater temperature may be used as an alternative

The present invention is mainly used in the winter season, but is not limited to the winter season and may of course also be used in the intermediate periods (spring and fall). As another embodiment, it is also possible to automatically switch the radiative heater ON/OFF in accordance with the target blowing-out temperature (TAO). That is, when the target blowing-out temperature is high, it is judged that it is the summer and the radiative heater is turned OFF, while when the target blowing-out temperature is low, it is judged that it is the winter and the radiative heater is turned ON.

In addition, the temperature setting of the air-conditioning unit (HVAC), the outside air temperature, the inside air temperature, the foot area temperature (value estimated by foot sensor and target blowing-out temperature etc.), or the seat heater temperature may be used as the basis for ON/OFF control of the radiative heater.

Third Embodiment

As shown in FIGS. 2A and 2B, when using the radiative heater 1, it is necessary that it be able to be used safely without concern over high temperature burn injuries and low temperature burn injuries. “High temperature burn injuries” mean burn injuries which instantaneously are caused, while “low temperature burn injuries” are burn injuries in which for example the skin is in contact with a 44° C. heat source for 6 hours whereupon the cells at that part are destroyed down deep under the skin resulting in burn injuries.

It is known that right after a passenger gets in a vehicle in the winter season, he or she easily feels cold due to the passenger compartment not being warmed up. Therefore, in particular, the foot parts are heated by local radiative heating using the radiative heater 1. In such a case, at the start of the heating, there is a concern that the temperature of the heating element 2 of the radiative heater 1 will rapidly rise and cause high temperature burn injuries. If heating the foot parts over a long period of time using the radiative heater 1, low temperature burn injuries will sometimes be caused. In the present embodiment, to enable safe use without concern as to such high temperature burn injuries and low temperature burn injuries, no matter how the temperature information inside the passenger compartment such as the target blowing-out temperature TAO, temperature setting T_(set), manual temperature setting of a radiative heater or seat heater, foot area temperature, etc. are set, the temperature of the heating element 2 of the radiative heater 1 is automatically controlled to be not more than the threshold temperatures for the high temperature burn injuries and low temperature burn injuries.

As a third embodiment of the present invention, the case where a radiative heater 1 is arranged for heating the foot parts and automatic air-conditioning control is performed will be explained.

At the start of heating, the foot parts are not sufficiently heated by just the air-conditioning unit (HVAC), so control is performed so that the temperature of the heating element 2 of the radiative heater 1 is rapidly raised and the foot parts, which are particularly susceptible to cold and heat in the body, are warmed. At this time, the temperature of the heating element 2 rises to over the low temperature burn injury threshold temperature where the skin surface will not suffer from low temperature burn injuries, but is maintained at less than the high temperature burn injury threshold temperature where the skin surface will not suffer from high temperature burn injuries.

FIG. 7A is one example of a graph which shows the relationship between the target blowing-out temperature TAO and the surface member temperature T of the heating element 2 at the transitional period where the elapsed time t from when the heating element 2 of the radiative heater 1 turned ON is t₁ or less, while FIG. 7B is one example of a graph which shows the relationship between the target blowing-out temperature TAO and the surface member temperature T of the heating element 2 at the steady state period where the elapsed time t exceeds t₁.

As shown in FIG. 7A, when the elapsed time t is t₁ or less, the heating element 2 of the radiative heater 1 is controlled to not more than the high temperature burn injury threshold temperature at which the skin surface will not suffer from high temperature burn injuries converted to the surface member temperature T of the heating element 2, that is, the high temperature burn injury threshold temperature T₁ (first upper limit value at which passengers will not suffer high temperature burn injuries).

When, finally, the inside of the passenger compartment is warmed, the target blowing-out temperature TAO falls. In this case, as shown in FIG. 7A, the surface member temperature T of the heating element 2 is also made to fall automatically proportional to the target blowing-out temperature TAO. If the inside of the passenger compartment is warmed and gradually approaches the temperature which the passenger desires, the target blowing-out temperature becomes a predetermined value α₀ or less and there is no longer a need to turn on the heating element 2. The heating element 2 is forcibly turned OFF. Note that, the predetermined value α₀ may be suitably set by experience from the need to turn the heating element 2 ON.

On the other hand, in the steady state period after the elapsed time T from when the heating element 2 of the radiative heater 1 was turned ON exceeds t₁ (in general, after about 1 or 2 hours), this time there is a concern over low temperature burn injuries. Therefore, as shown in FIG. 7B, the surface member temperature T of the heating element 2 is maintained at not more than the low temperature burn injury threshold temperature at which the skin surface will not suffer from low temperature burn injuries converted to the surface member temperature T of the heating element 2, that is, the low temperature burn injury threshold temperature T₂ (second upper limit value at which passengers will not suffer low temperature burn injuries). In the same way as in FIG. 7A, if the target blowing-out temperature becomes a predetermined value α₀ or less, there is no longer a need for turning on the heating element 2, so the heating element 2 is forcibly turned OFF. Note that, instead of FIG. 7B, control to any certain value of the low temperature burn injury threshold temperature T₂ or less may be performed.

In a vehicular heating system in which the radiative heater 1 is provided for heating the leg parts, when performing automatic air-conditioning control, it is possible to control the surface member temperature T of the heating element 2 of the radiative heater 1 while linked with the value of the target blowing-out temperature TAO. Due to this, safe use is possible without concern over high temperature burn injuries and low temperature burn injuries. In the winter season right after a passenger gets in the vehicle and feels cold due to the passenger compartment not being warmed up, the value of the target blowing-out temperature rises to a high temperature, but even in this case, the radiative heater is controlled to not more than the high temperature burn injury threshold temperature where high temperature burn injuries are not suffered and therefore the passenger compartment and feet area are quickly warmed.

After this, as the value of the target blowing-out temperature TAO falls, the surface member temperature T of the heating element 2 of the radiative heater 1 also automatically falls by the same timing, so the feet can be efficiently heated without waste. In this way, it is possible to maintain the warmness sense level in the foot area constant. Further, there is no waste in the heating by the heating element 2 of the radiative heater 1, so energy is saved. Further, in the steady state period when the elapsed time t exceeds t₁, it is possible to maintain the warmness sense level of the foot area constant while enabling use without concern over low temperature burn injuries due to use of the radiative heater 1.

FIG. 8 is a graph which shows the relationship of the foot area temperature, the heating element surface member temperature, and the warmness sense level with time. FIG. 8 shows one example of the advantageous effects due to the present embodiment. It is seen that the heating element surface member temperature at the center part compensates well for the delay in the rise of the foot area temperature and contributes to improvement of the warmness sense level. In this way, the radiative heater 1 contributes well to the rise of the temperature at the foot area in the transitional period and enables a predetermined warmness sense level to be kept without concern over low temperature burn injuries in the steady state period.

Next, the relationship of the burn injury threshold temperatures at which the skin surface will not suffer from high temperature burn injuries or low temperature burn injuries and the surface member temperature T of the heating element 2 and also the elapsed time t₁ will be explained briefly. There are many findings regarding high temperature burn injuries (instant burn injuries), but from the research findings of J.D. Hardy etc., the high temperature burn injury threshold temperature is set to a skin temperature of 60° C. In addition, it may be set around 60° C. or below that. Regarding low temperature burn injuries, it is known that if the skin is in contact with a 44° C. heat source for about 6 hours, the cells of that part will be destroyed down to a deep part under the skin and burn injuries will result. When viewed by the temperature in the skin and under the skin, burn injuries occur at 41.7° C. or more. From this, as one example, the low temperature burn injury threshold temperature is set to a temperature of the skin of 41.7° C., but it is also possible to set this at 40° C. or less for safety. Whatever the case, there are numerous discoveries regarding the high temperature burn injury threshold temperature and the low temperature burn injury threshold temperature. These may be determined by considering these.

FIG. 9 is an explanatory view of one example of a method for converting the burn injury threshold temperature at the temperature of the skin to a surface member temperature T of the heating element 2. It is possible to convert the burn injury threshold temperature at the temperature of the skin to the surface member temperature T from the heat transfer coefficient or thickness of the surface member of the heating element 2, so the radiative heater 1 is controlled as shown in FIGS. 7A and 7B by the heating element surface member temperature of the radiative heater 1 (high temperature burn injury threshold temperature T₁ and low temperature burn injury threshold temperature T₂). The high temperature burn injury threshold temperature T₁ is a first upper limit value where the passengers will not suffer from high temperature burn injuries, while the low temperature burn injury threshold temperature T₂ is a second upper threshold value where the passengers will not suffer from low temperature burn injuries. The heating element surface member temperature of the radiative heater 1 may be detected by a sensor, but the current value of the heating element may be used instead.

FIG. 10 is one example of a graph showing the relationship between low temperature burn injuries and time. Between 44 to 51° C., it is said that for every 1 degree rise in temperature of the heat source, the time which is required until a burn is caused is halved. Therefore, the time until suffering low temperature burn injuries cannot be unambiguously determined, so it is sufficient to refer to a graph such as FIG. 10 and suitably determine the elapsed time t₁ from when the heating element 2 of the radiative heater 1 is turned ON (critical point between transitional period and steady state period, switching point of control between FIG. 7A and FIG. 7B).

As other embodiments of the present invention, the following may be considered: In the above explanation, the radiative heater 1 was controlled linked with the temperature information of the value of the target blowing-out temperature TAO in automatic air-conditioning control, but the invention is not limited to this. Instead of the target blowing-out temperature TAO, it is also possible to utilize as the temperature information a temperature setting T_(set) at the time of automatic air-conditioning control to perform control the same as FIG. 7A and FIG. 7B. Furthermore, the temperature information may also be a temperature setting in the case of switching the operating mode to manual.

When the seat of a passenger is provided with a seat heater and the temperature setting of the seat heater can be set by a dial etc., the temperature setting of the seat heater may also be used as the temperature information. A “seat heater” is a heater which uses electric heating wires which are embedded in a seat so as to warm the seat. The radiative heater 1 is controlled in the same way as FIGS. 7A and 7B while linked with the temperature information of the temperature setting of the seat heater. In this case, the surface member temperature T of the heating element 2 of the radiative heater 1 is controlled as shown in FIGS. 7A and 7B while linked with the temperature setting of the seat heater. The temperature of a seat heater itself, in the same way as the surface member temperature T of the heating element 2, is limited by the elapsed time t to the high temperature burn injury threshold temperature T₁ and the low temperature burn injury threshold temperature T₂ or less.

Similarly, even if providing a sensor which detects the temperature of the foot area, it is possible to control the radiative heater 1 in the same way as in FIGS. 7A and 7B while linked with the temperature information of the temperature of the sensor which detects the temperature of the foot area. Similar control is also possible by estimating the foot area temperature from the value of the target blowing-out temperature TAO in addition to the sensor.

As explained above, it is possible to use various values as the temperature information and possible to control the surface member temperature T of the heating element 2 of the radiative heater 1 as shown in FIGS. 7A and 7B while linked to these temperature information. The temperature information is not limited to the information illustrated above.

FIG. 11 is a conceptual flowchart of an embodiment of the present invention. At step S100, it is judged if the elapsed time t from when the heating element 2 of the radiative heater 1 turns ON is t₁ or less. If YES, the routine proceeds to step S101, while if NO, the routine proceeds to step S102. At step S101 and step S102, it is judged if the temperature information indicates that the heating element 2 of the radiative heater 1 should be turned OFF. If YES, at step S105, it is turned OFF. At step S101 and step S102, if NO, the routine respectively proceeds to step S103 and step S104 where the control of FIGS. 7A and 7B is performed.

While the invention has been described with reference to specific embodiments chosen for purpose of illustration, it should be apparent that numerous modifications could be made thereto by those skilled in the art without departing from the basic concept and scope of the invention.

While the invention has been described by reference to specific embodiments chosen for purposes of illustration, it should be apparent that numerous modifications could be made thereto by those skilled in the art without departing from the basic concept and scope of the invention. 

1. A vehicular heating system comprising a passenger compartment air-conditioner with an air-conditioning unit controlling passenger compartment air-conditioning by calculating a target blowing-out temperature of said air-conditioning unit in accordance with information on the environment inside and outside of the passenger compartment and vehicle operating information, wherein a foot vent air flow of said air-conditioning unit being adjustable, and a radiative heater which heats a foot area of a passenger, said vehicular heating system detecting foot vent heat which said foot vent air flow has and controlling said passenger compartment air-conditioner and said radiative heater in accordance with that heat.
 2. A vehicular heating system as set forth in claim 1, wherein the system controls said passenger compartment air-conditioner and said radiative heater so that a ratio between the foot vent heat which said foot vent air flow has and the electric power input to the radiative heater gives the same warmness sense level at the feet of the passenger.
 3. A vehicular heating system as set forth in claim 2, wherein when the engine water temperature is a predetermined value or more, the system makes said foot vent air flow increase and makes the input electric power of said radiative heater decrease so that the ratio between the foot vent heat which said foot vent air flow has and the electric power input to the radiative heater gives the same warmness sense level at the feet of the passenger and when the engine water temperature is less than the predetermined value, the system makes said foot vent air flow decrease and makes the electric power input to the radiative heater increase so that the ratio between the foot vent heat which said foot vent air flow has and the electric power input to the radiative heater gives the same warmness sense level at the feet of the passengers.
 4. A vehicular heating system as set forth in claim 2, wherein when the engine water temperature is a predetermined value or more, the system turns said radiative heater OFF, when the engine water temperature is less than the predetermined value, the system turns said radiative heater ON and makes said foot vent air flow decrease and makes the electric power input to said radiative heater increase so that the ratio between the foot vent heat which said foot vent air flow has and the electric power input to the radiative heater gives the same warmness sense level at the feet of the passengers.
 5. A vehicular heating system as set forth in claim 2, wherein said foot vent air flow is a vent air flow of a foot vent.
 6. A vehicular heating system as set forth in claim 2, wherein said foot vent air flow is a total of the vent air flow of a foot vent and the vent air flow of a knee vent.
 7. A vehicular heating system as set forth in claim 2, wherein said system adjusts said foot vent air flow by a blower of said air-conditioning unit.
 8. A vehicular heating system as set forth in claim 2, wherein said system adjusts said foot vent air flow by a door opening degree of a foot vent of said air-conditioning unit.
 9. A vehicular heating system as set forth in claim 2, wherein said system adjusts said foot vent air flow by a door opening degree of a knee vent of said air-conditioning unit.
 10. A vehicular heating system as set forth in claim 3, wherein when the engine water temperature is less than a predetermined value, said system makes said foot vent air flow zero.
 11. A vehicular heating system as set forth in claim 2, wherein said system uses said target blowing-out temperature of the air-conditioning unit, said temperature setting of the air-conditioning unit, an outside air temperature, an inside air temperature, a foot area temperature, or a seat heater temperature as the basis to control said radiative heater ON and OFF.
 12. A vehicular heating system which adjusts a heating element surface member temperature of a radiative heater which warms a passenger in accordance with temperature information inside the passenger compartment, in which vehicular heating system before a predetermined time elapses from when heating by said vehicular heating system is turned ON or at the time of elapse, said heating element surface member temperature is controlled based on a setting for which a first upper threshold value where the passenger will not suffer high temperature burn injuries is set and which is set to increase proportionally or in a monotone functional way in accordance with temperature information inside the passenger compartment at below that upper threshold value, and after a predetermined time elapses from when heating by said vehicular heating system is turned ON, said heating element surface member temperature is controlled to not more than a second upper threshold value where the passenger will not suffer low temperature burn injuries.
 13. A vehicular heating system as set forth in claim 12, wherein said temperature information inside the passenger compartment is the target blowing-out temperature of the air-conditioning unit which controls the passenger compartment air-conditioning in accordance with information on the environment inside and outside of the passenger compartment.
 14. A vehicular heating system as set forth in claim 12, wherein said temperature information inside the passenger compartment is the temperature setting of the air-conditioning unit which controls the passenger compartment air-conditioning in accordance with information on the environment inside and outside of the passenger compartment.
 15. A vehicular heating system as set forth in claim 12, wherein said temperature information inside the passenger compartment is the temperature setting when an operating mode of the passenger compartment air-conditioning is manual.
 16. A vehicular heating system as set forth in claim 12, wherein said temperature information inside the passenger compartment is a foot area temperature.
 17. A vehicular heating system as set forth in claim 12, wherein said temperature information inside the passenger compartment is a manual temperature setting of said radiative heater.
 18. A vehicular heating system as set forth in claim 12, wherein said temperature information inside the passenger compartment is a manual temperature setting of a seat heater. 